AGW alarmist climate scientists predicted that increasing human CO2 emissions would cause an increase in water vapor with the result being a global warming tipping point - empirical evidence completely discredits that prediction
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Read here. Very simply, for the IPCC's climate models predicted runway global warming to happen, there has to be a positive feedback from atmospheric CO2 that pushes the climate to a "tipping point." The positive feedback in the IPCC's computer models is an ever increasing atmospheric water vapor level (greenhouse gas) due to rising temperatures from CO2.
In the real world though, that positive feedback has not happened, as the adjacent chart of relative humidity (atmospheric water vapor) and global temperatures shows. And now, a new peer reviewed study in the prestigious Journal of Climate is confirming that the global warming tipping point hypothesis is without any empirical merit.
"A paper published today in the Journal of Climate finds that relative humidity has been decreasing 0.5% per decade across North America during the 62 year period of observations from 1948-2010. Computer models of AGW show positive feedback from water vapor by incorrectly assuming that relative humidity remains constant with warming while specific humidity increases....."Over 1/4 billion hourly values of temperature and relative humidity observed at 309 stations located across North America during 1948-2010 were studied...The averages of these seasonal trends are 0.20 C/decade and 0.07 hPa/decade which correspond to a specific humidity increase of 0.04 g/kg per decade and a relative humidity reduction of 0.5%/decade."" [V. Isaac and W. A. van Wijngaarden 2012: Journal of Climate]